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Roland Documentation:

Changing 24-pin Connectors

From Original Pin-Type to Positive Locking Connectors

Thanks so much to Matteo Mannoni, who runs the Infernale Machine studio in France for sending along some rare documentation about the changes to the Roland GR-500 system, and the 24-pin connectors used in the GR-500, and later the GR-100, GR-300 and other vintage 24-pin synths.

Matteo sent me the original scan of this notice regarding the change from the original pin type, to the locking frame (positive type) used on the Roland connectors. This change is also documented on the cables page, and on the GR-500 page in the Versions section.

Curiously, Roland later switched back to the earlier pin system with the Roland GM-70 and GK-1, and the Roland GR-77B bass synthesizer, and G-77 bass guitar system.


Due to specification changes, newer model Guitar Synthesizers are equipped with new type positive locking connectors.




roland c-c4b connector arrow roland c-c4c connector
Use the C-24B Cable with Guitar
Synthesizers equipped with
the old type connectors.
  Use the C-24C Cable with Guitar
Synthesizers equipped with
the new type connectors.



GR-500 connecting Pull lock open.  


connecting 2 connecting 3 Insert connector


connecting 4 connecting 5 Lock connector.


The old type C-24B Cable can be used with either old or new type connectors.

It is possible to use the new type C-24C Cable with the old style connectors, but this is not recommended because this arrangement provides no locking feature and the connectors can be easily separated.

*The connectors are keyed so that they cannot be connected n the wrong way.